It’s new and exciting for Andy Murray and Angelique Kerber, entering a Grand Slam tournament with the No. 1 in front of their names.Both reached the top of the rankings for the first time near the end of 2016, ending long reigns by Novak Djokovic and Serena Williams.And so they’ll open their Australian Open campaigns on Rod Laver Arena on day one – both against Ukrainians.Murray, a five-time runner-up, opens his pursuit of a first Australian title against Illya Marchenko in the last-day match on the main show court. Kerber opens the night session against Lesia Tsurenko. She’ll be followed on court by Roger Federer, who is returning from six months on the sidelines.The ‘one-round-at-a-time’ clichÈ is well worn in tennis. For Kerber, though, it’s pertinent. Seeded seventh last year, the left-handed German had to save a match point in the first round against Misaki Doi. Spurred on by that, she went on to beat Serena Williams in the final and claim her first Grand Slam title. She added a second major at the US Open and ascended to the No. 1 ranking.”I think this point where I was match point down, that was the important point for my career,” Kerber said yesterday, speaking of her first-round escape against Doi. “You never know (if) I lost the match, what would have happened.”WITHOUT PRESSUREIt gave her the freedom to play without pressure, and that made all the difference.”When I’m looking back, I was feeling that I got a second chance to stay in the tournament,” she said. “I was playing since then without expectation … just enjoying everything.”Kerber can hang on to the top ranking by reaching to the final here, but she’s already feeling there’s more to defend than her title.”It’s a new challenge for me, for sure,” she said, but we are starting from zero here. I have to be ready from the first round again.”I will try to not put too much expectation and pressure on myself. I mean, I will try to do it like last year – that was the way I had my success.”Record-chasing, six-time champions Djokovic and Williams, seeded No. 2 and anchoring the bottom half of the men’s and women’s draws, won’t be in action until day two. Djokovic is aiming to be the first man to win seven Australian titles. Serena Williams is chasing an Open-era record 23rd major title.